Chronic allograft rejection is the leading cause of renal and cardiac allograft failure. The Long term goal of this core is to assist investigators in acquiring the experimental data necessary for the successful investigation of this disease process. In this program project human cardiac biopsies will be extensively utilized, as well as murine cardiac grafts, for the investigation of chronic rejection; however, meaningful studies with model will require the use of standardized tissue sections, special stains, and quantitative morphometric measurements. Therefore, the short term goals of the Histopathology core are to provide a centralized and standardized histology, immunohistochemistry, and automated morphometric analysis service for all projects. As a central core service it will guarantee a high level of uniformity, consistency and quality that will facilitate comparison of experimental results between the three program projects. The Specific Aims are to (1) provide a central histopathology laboratory for all projects, (ii) provide a central immunohistochemistry laboratory for the detection of disease-related antigens in frozen or formalin-fixed tissues, (iii) provide an automated image analysis and morphometrics service that will provide consistent and uniform measurements of transplant vascular sclerosis and myocardial fibrosis in murine heterotopic heart transplants and human explanted heart autopsy specimens, and (IV) provide a laser capture microdissection (LCM) service that will provide morphometric-like cell populations from thin sections of formalin fixed paraffin-embedded or frozen tissues of both animal and human tissues for molecular analysis. The core will be located in The Ohio State University Medical Center and utilize the pre-existing Department of Pathology laboratories.